diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 4f96699e363..472c206f64c 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -10,6 +10,7 @@
 #include <config.h>
 #include <fat.h>
 #include <malloc.h>
+#include <vsprintf.h>
 #include <asm/byteorder.h>
 #include <part.h>
 #include <linux/ctype.h>
@@ -17,16 +18,6 @@
 #include <linux/math64.h>
 #include "fat.c"
 
-static void uppercase(char *str, int len)
-{
-	int i;
-
-	for (i = 0; i < len; i++) {
-		*str = toupper(*str);
-		str++;
-	}
-}
-
 static int total_sector;
 static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
 {
@@ -65,7 +56,7 @@ static void set_name(dir_entry *dirent, const char *filename)
 		return;
 
 	strcpy(s_name, filename);
-	uppercase(s_name, len);
+	str_to_upper(s_name, s_name, len);
 
 	period = strchr(s_name, '.');
 	if (period == NULL) {
diff --git a/include/vsprintf.h b/include/vsprintf.h
index 56844dd2de8..d3f1292ae4d 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -222,4 +222,16 @@ bool str2long(const char *p, ulong *num);
  * @hz: Value to convert
  */
 char *strmhz(char *buf, unsigned long hz);
+
+/**
+ * str_to_upper() - Convert a string to upper case
+ *
+ * This simply uses toupper() on each character of the string.
+ *
+ * @in: String to convert (must be large enough to hold the output string)
+ * @out: Converting string
+ * @len: Number of characters to convert (-1 for all)
+ */
+void str_to_upper(const char *in, char *out, int len);
+
 #endif
diff --git a/lib/strto.c b/lib/strto.c
index 55ff9f7437d..563892a52c0 100644
--- a/lib/strto.c
+++ b/lib/strto.c
@@ -163,3 +163,11 @@ long trailing_strtol(const char *str)
 {
 	return trailing_strtoln(str, NULL);
 }
+
+void str_to_upper(const char *in, char *out, int len)
+{
+	while ((len == -1 || len-- > 0) && *in)
+		*out++ = toupper(*in++);
+	if (len && !*in)
+		*out = '\0';
+}
diff --git a/test/str_ut.c b/test/str_ut.c
index 0ce6b055792..09726b076fe 100644
--- a/test/str_ut.c
+++ b/test/str_ut.c
@@ -19,36 +19,73 @@ static const char str3[] = "0xbI'm sorry you're alive.";
 /* Declare a new str test */
 #define STR_TEST(_name, _flags)		UNIT_TEST(_name, _flags, str_test)
 
+static int str_test_upper(struct unit_test_state *uts)
+{
+	char out[TEST_STR_SIZE];
+
+	/* Make sure it adds a terminator */
+	out[strlen(str1)] = 'a';
+	str_to_upper(str1, out, -1);
+	ut_asserteq_str("I'M SORRY I'M LATE.", out);
+
+	/* In-place operation */
+	strcpy(out, str2);
+	str_to_upper(out, out, -1);
+	ut_asserteq_str("1099ABNO, DON'T BOTHER APOLOGISING.", out);
+
+	/* Limited length */
+	str_to_upper(str1, out, 7);
+	ut_asserteq_str("I'M SORO, DON'T BOTHER APOLOGISING.", out);
+
+	/* In-place with limited length */
+	strcpy(out, str2);
+	str_to_upper(out, out, 7);
+	ut_asserteq_str("1099ABNo, don't bother apologising.", out);
+
+	return 0;
+}
+STR_TEST(str_test_upper, 0);
+
 static int run_strtoul(struct unit_test_state *uts, const char *str, int base,
-		       ulong expect_val, int expect_endp_offset)
+		       ulong expect_val, int expect_endp_offset, bool upper)
 {
+	char out[TEST_STR_SIZE];
 	char *endp;
 	ulong val;
 
-	val = simple_strtoul(str, &endp, base);
+	strcpy(out, str);
+	if (upper)
+		str_to_upper(out, out, -1);
+
+	val = simple_strtoul(out, &endp, base);
 	ut_asserteq(expect_val, val);
-	ut_asserteq(expect_endp_offset, endp - str);
+	ut_asserteq(expect_endp_offset, endp - out);
 
 	return 0;
 }
 
 static int str_simple_strtoul(struct unit_test_state *uts)
 {
-	/* Base 10 and base 16 */
-	ut_assertok(run_strtoul(uts, str2, 10, 1099, 4));
-	ut_assertok(run_strtoul(uts, str2, 16, 0x1099ab, 6));
-
-	/* Invalid string */
-	ut_assertok(run_strtoul(uts, str1, 10, 0, 0));
-
-	/* Base 0 */
-	ut_assertok(run_strtoul(uts, str1, 0, 0, 0));
-	ut_assertok(run_strtoul(uts, str2, 0, 1099, 4));
-	ut_assertok(run_strtoul(uts, str3, 0, 0xb, 3));
-
-	/* Base 2 */
-	ut_assertok(run_strtoul(uts, str1, 2, 0, 0));
-	ut_assertok(run_strtoul(uts, str2, 2, 2, 2));
+	int upper;
+
+	/* Check that it is case-insentive */
+	for (upper = 0; upper < 2; upper++) {
+		/* Base 10 and base 16 */
+		ut_assertok(run_strtoul(uts, str2, 10, 1099, 4, upper));
+		ut_assertok(run_strtoul(uts, str2, 16, 0x1099ab, 6, upper));
+
+		/* Invalid string */
+		ut_assertok(run_strtoul(uts, str1, 10, 0, 0, upper));
+
+		/* Base 0 */
+		ut_assertok(run_strtoul(uts, str1, 0, 0, 0, upper));
+		ut_assertok(run_strtoul(uts, str2, 0, 1099, 4, upper));
+		ut_assertok(run_strtoul(uts, str3, 0, 0xb, 3, upper));
+
+		/* Base 2 */
+		ut_assertok(run_strtoul(uts, str1, 2, 0, 0, upper));
+		ut_assertok(run_strtoul(uts, str2, 2, 2, 2, upper));
+	}
 
 	/* Check endp being NULL */
 	ut_asserteq(1099, simple_strtoul(str2, NULL, 0));
